Threading implement



Oct. 20, 1959 o. R. POWELL THREADING IMPLEMENT 2 Sheets-Sheet 1 Filed Oct. 17. 1956 INVENTOR. DAVID R. POWELL Oct. 20, 1959 n. R. POWELL 2, 8

THREADING IMPLEMENT Filed Oct. 17, 1956 2 Sheets-Sheet 2 INVENTOR. DAVID R. POWELL 2,909,037 THREADING IMPLEMENT David R. Powell, Euclid, Ohio, assignor t6 The National Acme Company, a corporation of Ohio Application October 17, 1956, Serial N6. 616,400

1 1 Claim. c1. 80-6) The invention relates in general to threading implements and. more particularlyto a thread rolling die or head forrollingthreads on a workpiece. The invention has special application to a self-opening threading implement such as a collapsing tap or. a self-opening d e head, and the preferred embodiment of'the invention is illustrated in the drawings as being applied to a thread rolling head which is of the self-opening type and which is Universal in application in that it may be used either as. a stationary or a rotating roll head.

Self-opening thread rolling heads have been known in the prior art but one primary difliculty was that two different types of heads were required, one for stationary use and the other for rotating use. Also, in the prior art thread rolling heads there was a decided disadvantage in that the self-opening types frequently had. thread rolls or threading tools which could not move out of the way fast enoughduring the opening of the head at the end of the rolling operation, and thus these rolls struck the threads to mark and partially deform the same. This made the threads defective for close tolerance applications because they would not have a true thread shape. This marking of the threads primarily occurred at the higher peripheralrolling speeds and thus was a limitation on the speed of rolling andhence a limitation on production of a machine employing such a prior art form of roll head.

An object of the present invention therefore is to provide a threading'implement or thread rolling head which may be used for either stationary or rotating applications with the identical basic rolling head being used in each case to thus be a universally applicable threading implement.

Another object of the invention is to provide a selfopening threading implement which may be used at very high peripheral rolling speeds, yet which does not mark the threads at any time. even during opening of the die head.

Another object of the invention is to provide a simple construction of thread rolling head which may be used' as a rotating head and which will, after opening, be easily reset to the thread forming position by use of a friction yoke for momentarily slowing the frame of the thread rolling head.

Another object of the invention is to provide a thread rolling'head which may be closed by use of inertia. 7

Another object of the invention is to provide an opening type of thread rolling head wherein, as the head opens, the head rotates in the same direction as it rotates for the threading operation and the rolls themselves also move on eccentrics outwardly away from the workpiece and in the same direction of rotation with the movement of the thread rolls having an axial component which is in the same direction as the threading advancement of the die head on the workpiece. v This axial movement is in a forward direction to avoid marking or defacing the workpiece threads which could otherwise occur if the-rolls did not move quickly enough away from the workpiece.

Other objects and a. fuller understanding of i vention may be had by, referring to the followingdescrip' in conjunction with the QQCOHl-y tion and claim, taken v panying drawings, in which: t v Figure 1 is a front elevational'view of a thread rolling head embodying the invention}.

Figure 2 is a longitudinal sectional View of the:

of Figure 1;

Figure 3 is 'a rear elevational view of headito a smaller scale;

Figures 4 and 5 are sectional viewson the lines and 5-5 of Figure 2 to ya smaller scale;

Figure 6 is a partial side clutch; and

Figure 7 is an explanatoryview of a thread a workpiece.

The invention may generally be used on many forms of threading implements such as. taps or dies,,and .the. drawings and the following description show the invention applied to one form of threading. implement, namely, a.

thread rolling head 11, with such description being made for the purpose of illustration 7 thread rolling head 11 includes a frame 13 with the shank 12 chucked in the machine tool with which the thread rolling head 11 is to be used. The shank 12 has an axis 15 and the frame 13 is coaxial with this shank 12. 5 v

generally a shank 12 and The frame 13 is adapted to carry 'a pIuraIityof ingtools or thread'fforming 'tools-16-', in thiscase shown as thread rolls 17,18, and 19.- In the headjllsh own in are" used, although-com:-

the drawing, the'three such rolls I monly two are used on the smaller heads, and actually any plurality may be used. I v The frame 13 includes a front plate'23 and amiddle plate 24 held in spaced relationship by'space'rs 25 and bolts 26. A rear plate 28 has arcuate slots 29 therein,

and studs 30 carried in the middle plate/24 extend throughthese. slots 29 and are engagedby 'nutsi31 to hold'the middle and rear plates together;

is journalled the thread 011 16. 'The inboard end .35 of each of the spindles fixedly shank '12; The spindles 33 seen in Figure 2, with the axis of the thread roll lying in a plane parallel to the plane 'containing the axis '15.

Each thread roll 16 has annular grooves thereon and this to accommodate the slight skewing of the spindle axes. A

28,;and'a com mounted in the. recess with one end fastened to the shank 12 and the recess 40 is provided in the rear plate bined tension and torsion spring 41 is other end fastened to the rear plate 28.

This spring 41 interconnects the shank 12 and the'frame 13 to urge the frame in a first rotational direction relative to the shank'i which is counterclockw'ise'as viewed in'FigureI. This spring '41 is also wound in'a generally conical shape so;

that it has a natural resiliency tending to resume the conical shape; and when stressed into the generally'flat plane as shown in Figure 2, it acts as the shank, namely, viewed in Figure 2;

A dog clutch 44 interconnects the shank IZand frame 13 and is formed of -a first clutch part 4 5 o'n'the 12;. part" 46 on'the re'a'r plate 28. "The and a seoond clutch elevation sho thefadg,

and not limitation. Theadapted to be gripped or;

A plurality of spindles 33 are journalled in the front and middle" plates 23 and' 24 with a spindle 'foreach of the thread rolls. 16. Each of these spindlesfhas an eccentric; portion 34fo'n which carries a pinion "36 which meshes with a central gear .37 slidably splined on the are symmetrically placed relative to the axis 15, and each axis is skewed, as bestl The pinions v 36 'a tension spring; to urge the frame 13 in a first axial direction relative. to to urge the frame 13 toth eright asj frame 13may slide axially relative to the shank between limits to engage the dog clutch 44', as shown in the draW-' is'a'disengagedposition of the dog clutch and yet un'ges' the frame 13 in a first axial direction relative to the shank 12 which is toward an engaged position of the dog clutch 44. The interior of the shank 12 'is'preferably 'hollowand may be threaded at 49.toreceive a nut 50 in which is received a threaded internal adjustable stop 51. The stop 51 has an abutment end 52 for selected engagement with a workpiece, such as the workpiece 54 shown in Figure 7, as this workpiece is being threaded by the thread rolls 16. Such-threading engagement between the workpiece 54 and the thread rolls causes relative axial advancement of the-diehead' 11 onto the workpiece and, at the adjustable limit set by the position of the adjustable stop 51,

the abutment of the workpiece and the stop 51' causes axial separation of the dog clutch 44.

A cam handle 55 may be. attached to the rear face of therear plate 28 to elf'ect rotation of theframe 13 relative to the shank 12. This cam'handle 55 may have a cam surface 56 thereon for engagement by a cam on the machine tool with which the die head is used, or it may have a knob, not shown, for manual manipulation of the cam handle 55 and of the frame 13. The rear plate 28 is provided on the outer peripheral surface thereof with a tapered shoulder 58 for engagement by a friction yoke 59 which is apart of a friction clutch to engage this tapered shoulder 58. The friction yoke may be used whenthe head 11. is a rotating head, and in' such case the yoke 59 is rotatively stationary but axially movable tothe right, as viewed in Figure 2, to engage the tapered shoulder 58.

Operation The thread rolling head 11 may be used either as a stationary or as a rotating head depending upon the type of machine tool with which it is to be used. For turret lathes, single spindle automatics, multiple spindle automatics, and similar machine tools the work generally r tates, and in such case the diehead 11 would be mounted to be, rotatively stationary and would be mounted with the shank 121 in a stationary chuck, for example. In. bolt threading or similar machines it is common for the workpiece to be stationary with the die head rotating, and in "such case the shank 12 would be mounted in a rotating'chuck or spindle. In any machine tool it may b'e the workpiece which axially advances, or it may; be the'die head which axially advances, orit may be a combinationof both. I

The die head His a. self-opening die head and the drawing shows. this diehead in the closed position with the thread rolls 16 in their closed or most closely spaced position which. is an operative position for rolling threads onthe workpiece 54. Relative rotation between the.

workpiece and the die head must be provided for thread rolling. as well, as relative axial movement between the two. at leastfor the first two or three threads, and after that action of the formed threads on the workpiece meeting with the thread rolls is enough to pull the workpiece through the die head or converselyto pull the die head 11 axially onto the workpiece. until. theworkpiece 54 engages the adjustable stop 51. Continuedrelative rotation between the workpiece and the die head moves the adjustable stop 51 relatively to the right, as viewed in Figure 2, to disengage the dog clutch 44. I This dog clutch has six sixty degree portions.

and. the release of the dog clutch against the tension urging of the. spring 41 permits the torsion urging of this spring to rotate the frame 13 relative to the shank 12 in a counterclockwise direction, as viewed in Figure l.v

This rotation is for about sixty degrees, namely, the arcuate distance between steps, on-the dog clutch. Dursixty degree counterclockwise rotation of, the.

This action continues Figure l and Figure 4, the rolling operation. of right frame 13, the central gear 37 is relatively stationary be cause it is carried on the shank 12. The pinions 36, how ever, roll on this central gear 37 because the frame 13 is rotating counterclockwise. Figure 4 shows the action of the eccentrics 34, and considering for a moment that during the disengagement of the dog clutch it is the shank 12 which is rotating clockwise with the frame 13 rotationally stationary, for the particular thread roll 19, the axis 20 of its spindle is stationary and the axis 21 of the eccentric 34 is about at the ten oclock position. This is for the closed position of the dog clutch 44. As the dog clutch is disengaged and the shank 12 and frame 13 relatively rotate, the axis 21 rotates in a counterclockwise direction around the axis 20 for about ninety degrees to about the seven oclockposition whereat the thread roll 19 will be at the dot-dash position as shown in Figure 4. The dot-dash position of the thread roll 19 is the first limit position of the thread rolls relative to the workpiece, and the solid linefposition of the. thread. roll 19 of Figure 4 is the second-limit position of the. frame 13 and of the thread rolls 16, which isthe enthat the frame 13 moves clockwise relative to the shank.

12. When the frame has been rotated approximately sixty degrees clockwise, the tension urging of the spring 41 will pull the dog clutch 44 into engagement. This manual operation of the cant handle 55. would be when the die head 11 was used as a stationary die head.

When the die head 11 is used as a rotating head, it is. not convenient to stop the rotation thereof each time in.

order to manipulate the .handle 55. In such case the entire cam handle 55. is removed. by removing the bolt. holding same and the friction, clutch. or friction yoke 59- is used instead. This friction yokemay be mounted on the machine tool to be positioned close to the tapered shoulder 58 as shown in Figure 2.. Movement to the right of the friction yoke 59 will cause frictional engagement between the yoke and the shoulder 58. The entire head 11 rotates counterclockwise, as shown in Figure 1, for forming right hand threads on workpieces,v

and frictional engagement at the shoulder 58 would tend to retard the counterclockwise rotation of the frame 13. This would mean that the frame 13 was rotated clockwise relative to the shank 12 to reset the dog; clutch. 44 after the die head had opened in its self-opening action as described above.

The opening action of the die head 11, it will be noticed, is in the same direction as rotation of this head 11 and frame 13 during rolling operation. As. viewed in hand threads is performed by having the head rotate counterclockwise relative to the workpiece which, of course, includes the fact that the head can be stationary and the workpiece rotate clockwise. This counterclock wise rotationof the frame 13 is also accompanied in. its opening action by having the frame -13 also rotate counterclockwise under torsion action of the spring, 41. At the same time the axes of the spindles 33 rotate coun terclockwise, the pinions 36 rotate counterclockwise, and

the eccentrics 34 also move counterclockwise. The action, as explained above, in having the eccentrics movefrom the ten oclock position to the seven oclock position during the self-opening action is such as to. cause the thread rolls to move in a combined movement which is both radially outward androtationally in the same direction as the former thread rolling action. 7 This coupled with the fact that the axes of the rolls are skewed means.

that the entire rolls, and specifically the periphery of the rolls which formerly had been in. contact with the.

workpiece, move in the direction of the arrow 61 asshown. in Figure 7 This arrow is neither parallel to nor.- per-.-

pendicular to the axis rather it has a perpendicular component 62 and an axial component 63. This axial component is in the forward direction that is, in the direction of the axial movement of the rolling action of the die head 11 relative to the workpiece 54.

In prior art opening type of die heads it had been the practice to move the thread rolls outwardly for the opening action but to combine this with a rotational movement which was in the opposite direction from the thread rolling movement, such as indicated by the arrow 66. It will be noted that this movement, denoted by the arrow 66, has a rearward axial component 67. Such rearward axial component moved the thread rolls backwardly relative to the workpiece and, if one attempted to raise the peripheral rolling speed too high, the thread rolls could not get radially or laterally away from the axis 15 quickly enough; and therefore, the thread rolls marked the rear face of the threads as at 68 and 69. This was at three spaced places on all the threads as caused by the three thread rolls. In an attempt to overcome this marking of the threads which defaced them and made them so that they were not true threads, the prior art type of rolling heads attempted to use stronger and stronger torsion springs to get quicker opening action. This was successful only in part but, as still higher peripheral thread rolling speeds were used, the marking continued despite the fact that the stress of the torsion spring was increased to the danger point whereat the head was battering itself to pieces at the dog clutch 44. In contradistinotion, the thread rolling head of the present invention permits use of a torsion spring 41 stressed very much less, yet the fact that the thread rolls open forwardly in the direction of the rolling action gives the forward axial component 63 which prevents any markings whatever of the threads on the workpiece '54. This is a very decided advantage in rolling acceptable production workpieces.

A second definite advantage in the rolling head of the present invention is the fact that with the opening action being forward, that is, in the direction of the rolling action, one may use the die head 11 in a universal application, for either stationary or rotating applications. This is because the friction drag of the stationary yoke 59 on the tapered shoulder 58 is in the right direction to retard the rotation of the frame 13 so as to re-engage the dog clutch 44 and reclose the die head for the next thread rolling operation.

Another advantage of the present invention as incorporated in the die head shown is that this die head may also be closed by inertia. The frame 13 has very much more inertia than the shank 12 and, when this die head 11 is used as a rotating head, one may momentarily shut off the power to the spindle drivin g the shank 12 to decelerate the shank 12 and then re-apply the power which causes quick acceleration of the spindle and the shank 12. This quick acceleration can overcome the stress of the torsion spring 41 because of the inertia of the frame 13 to reset the head to the closed or operative position. This inertia closing of the die head 11 may be effected on many machine tools by having the die head as carried on an axially movable slide momentarily trip an electrical switch as the die head retracts on its slide. This switch can control power to the motor driving the spindle which drives the shank 12 to thus reclose this die head 11 as the slide retracts for the next rolling operation.

When the die head 11 is used in stationary applications, the cam surface 56 may be used to be engaged by a movable cam on the machine tool which periodically engages this cam surface 56 to reset the die head between each thread rolling operation. Thus, this head 11 is easily adapted to fully automatic operation so that an operator need not manually reset the head between each rolling operation.

The adjustable stop 51 may be moved axially to any desired position and may even be removed for long thread ing operations or if its use is not needed. In any rolling operation, whether used as a stationary or a rotating head, there is relative axial movement between the workpiece and the die head 11. If the machine tool using such die head has physical stops limiting this relative axial movement, this can be used to limit the length of thread rolling action and will control a point of pull off whereat the dog clutch 44 will become disengaged to open the die head 11. The gear 37 and pinion 36 forms a linkage interconnecting the eccentrics 34 and the shank 12 to move the thread forming tools or rolls 16 between the first and the'second limits, namely, either open or closed positions. The dog clutch forms a lock means to hold the frame at the second limit and also to hold the rolls at the second limit which is the operative position of the head 11. The relative axial movement of the workpiece and the die head during thread rolling operation used with or without the adjustable stop 51 to effect a disengagement of the dog clutch 44.

Although this invention has been described in its pre ferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

A threading implement comprising, a shank adapted for rotation about its axis, a frame coaxial with said shank and movable between first and second limits in first and second rotational directions, respectively, relative to said shank, a plurality of eccentrics journalled in said frame symmetrically placed relative to said axis, a thread forming tool carried on each of said eccentrics, means interconnecting said eccentrics and said shank to position said thread forming tools in an operative position at said second limit, means for urging said frame relative to said shank in said first rotational direction toward said first limit, lock means for holding said frame at said second limit, intermeshing faces on said lock means permitting movement in said first rotational di rection of said frame relative to said shank upon release of said lock means, said threading implement being rotatable in said first rotational direction relative to any said workpiece to form a thread thereon with consequent movement of said workpiece in a first axial direction relative to said implement, a braking surface on said frame adapted for engagement by a friction brake, means to effect release of said lock means to allow said frame to rotate in said first rotational direction relative to said shank under action of said urging means, rotation of said frame in said first rotational direction relative to said sank causing rotation of said eccentrics in said first rotational direction to move said thread forming tools laterally away from said workpiece and in the same direction of rotation as said frame with the movement of the pe riphery of the thread forming tools having an axial component in the second axial direction, engagement of said braking surface during rotation of said shank in said first rotational direction creating a frictional drag on said frame to move said frame in said second rotational direction relative to said shank against the rotational urging of said urging means to said second limit to re-engage said lock means.

References Cited in the file of this patent UNITED STATES PATENTS Erdelyi Sept. 8, 1953 Erdelyi et al. Oct. 18, 1955 

